package com.gitee.feizns.utils.encryption;

import com.sun.org.apache.xpath.internal.operations.String;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Security;

/**
 * DES 对称加密
 */
public abstract class DesUtils {

    //KeyGenerator 提供对称密钥生成器的功能，支持各种算法
    private static KeyGenerator keygen;

    //SecretKey 负责保存对称密钥
    private static SecretKey deskey;

    //Cipher负责完成加密或解密工作
    private static Cipher c;

    //该字节数组负责保存加密的结果
    private static byte[] cipherByte;

    static {
        Security.addProvider(new com.sun.crypto.provider.SunJCE());
        //实例化支持DES算法的密钥生成器(算法名称命名需按规定，否则抛出异常)
        try {
            keygen = KeyGenerator.getInstance("DES");
            //生成密钥
            deskey = keygen.generateKey();
            //生成Cipher对象,指定其支持的DES算法
            c = Cipher.getInstance("DES");
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            e.printStackTrace();
        }
    }

    /**
     * 对字符串加密
     *
     * @param src
     * @return
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public static byte[] encrypt(byte[] src) throws InvalidKeyException,
            IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
        // 根据密钥，对Cipher对象进行初始化，ENCRYPT_MODE表示加密模式
        c.init(Cipher.ENCRYPT_MODE, deskey);
        // 加密，结果保存进cipherByte
        cipherByte = c.doFinal(src);
        return cipherByte;
    }

    /**
     * 对字符串解密
     *
     * @param buff
     * @return
     * @throws InvalidKeyException
     * @throws IllegalBlockSizeException
     * @throws BadPaddingException
     */
    public static byte[] decrypt(byte[] buff) throws InvalidKeyException,
            IllegalBlockSizeException, BadPaddingException {

        c.init(Cipher.DECRYPT_MODE, deskey);
        cipherByte = c.doFinal(buff);
        return cipherByte;
    }

}
